During the afternoon & evening of May 24, 2011, a series of tornadic supercells moved across the southern plains in a classic High Risk scenario. The Norman, OK NWS has a website with detailed data on this event at this link.
Let’s first take a look at a large HP supercell that produced an EF-5 tornado that moved across central OK. This is Tornado B2 on the Norman NWS storm survey map.
At the time of this scan, a large wedge tornado had just crossed I-40 northwest of El Reno, OK. Several vehicles were blown off the interstate. The extensive precipitation core to the north contained very strong winds, heavy rain, and large hail.
The Storm Relative Velocity (SRV) scan at 2127 UTC shows a well developed couplet just northwest of El Reno, OK. At this time, a large wedge tornado had just crossed I-40. One video taken by a Univ. of Oklahoma research team showed the tornado developing an unusually large horizontal vortex on the northwest side of the main multiple vortex structure.
The BV scan at 2201 UTC is one of the more dramatic images that I captured during the outbreak. A large ‘debris ball’ can be seen in extreme southeast Kingfisher County, OK. By the time this scan was taken, the tornado had reached maximum intensity and was in the process of doing EF-5 damage. Near Piedmont, two young boys (age 15 months and 3 years) from a family of five were killed as their home was destroyed. The younger boy was found soon after the tornado. The remains of the older boy were carried some distance from the family home and were not found until two days after the tornado. The daughter and pregnant mother of the family were also hospitalized with injuries sustained during the storm. All together, this tornado killed nine people along a path that ran approximately 65 miles. The Norman, OK NWS has a detailed survey of this tornado at this link. The link also provides information on the tornado’s passage very near the El Reno Oklahoma Mesonet site where a peak wind gust of 151 m.p.h. was recorded.
The SRV scan at 2201 shows a classic strong mesocyclone couplet over the area where the BV product for the same time shows a debris ball. The tornado was close to one mile in width at this time and winds were well within the EF-5 range based on damage surveys. The tornado continued through Logan County, OK and disipated about four miles northeast of Guthrie, OK after a life span of approximately one hour & fourty-five minutes. This was a truly remarkable event in mesoscale meteorology and the second EF-5 tornado to occur in the United States in 48 hours (the first being the Joplin EF-5 of 22 May 2011).
Farther to the south in Grady County, OK, another tornadic supercell was moving towards the OKC metro. From the BV scan at 2205, you can see a classic reflectivity image with a hook echo.
A few minutes later at 2214, the BRV shows a significant couplet near Chickasha, OK. A large tornado was in progress at the time of this scan.
In the next BR image, a debris ball can be seen on the hook echo. The tornado had intensified as was moving along a path that paralleled the Bridge Creek/Moore/OKC tornado of 3 May 1999.
At 2239, we have a closer view of the BV scan of the Chickasha supercell. A pronounced hook echo is still visible as the tornado continued northeast and was very near the town of Newcastle, OK.
The SRV scan at 2239 shows a substantial couplet. At the time of this image, a large wedge tornado was in progress and there was considerable concern that it may move into parts of Norman or southern OKC.
In the last SRV scan, a dramatic image of a substantial couplet can be seen. At this time, a large wedge tornado was in progress that would be rated EF-4 in intensity.
The Chickasha tornadic supercell resulted in 1 fatality and 15 injuries. The tornado lasted for almost one hour and traveled 32 miles. During it’s most intense stage, it took on a wedge structure and, according to photos from the Norman NWS, removed asphalt from one road and swept the foundation of one structure of all debris. Across the Norman forecast area, one tornado has been rated EF-5, two were rated EF-4, two more rated EF-3, one EF-2, and three each rated EF-1, and EF-0. Hail to the size of 3″ in diameter was also reported.
In spite of the intensity of the tornadoes and the many long-track events that occurred, this outbreak could have been much worse. Most of the tornadoes stayed in rural areas or only gave small towns a glancing blow. Damage was significant in a handful of areas, but there was no widespread damage on the scale that was seen during the 27 April 2011 outbreak. Overall, I think many Oklahoma cities & towns dodged a bullet on this day. Considering the parameters that existed, we should feel fortunate that a worse case scenario was avoided…and it would serve us well to always remember than nature always has the upper hand.